Drug toxicity and viral resistance limit the long-term efficacy of antiviral drug treatment for human immunodeficiency virus (HIV) infection. Thus, alternative therapies need to be explored. We tested the infusion of T lymphocytes transduced with a retroviral vector (M87o) that expresses an HIV entry-inhibitory peptide (maC46). Gene-modified autologous T cells were infused into ten HIV-infected patients with advanced disease and multidrug-resistant virus during anti-retroviral combination therapy. T-cell infusions were tolerated well, with no severe side effects. A significant increase of CD4 counts was observed after infusion. At the end of the 1-year follow-up, the CD4 counts of all patients were still around or above baseline. Gene-modified cells could be detected in peripheral blood, lymph nodes, and bone marrow throughout the 1-year follow-up, and marking levels correlated with the cell dose. No significant changes of viral load were observed during the first 4 months. Four of the seven patients who changed their antiviral drug regimen thereafter responded with a significant decline in plasma viral load. In conclusion, the transfer of gene-modified cells was safe, led to sustained levels of gene marking, and may improve immune competence in HIV-infected patients with advanced disease and multidrug-resistant virus.

The immunological and virological impact of short-term treatment initiated during acute human immunodeficiency virus type 1 (HIV-1) infection was assessed prospectively in 20 subjects, 12 of whom initiated highly active antiretroviral therapy (HAART) for 24 weeks and then terminated treatment. Treatment resulted in suppression of viremia, an increase in the CD4+ T cell count, enhanced differentiation of HIV-1-specific CD8(+) T cells from effector memory to effector cells at week 24 of HAART, and significantly higher virus-specific interferon- gamma+ CD8+ T cell responses after viral rebound (at week 48). However, despite these immunological changes, no differences in viremia or in the CD4+ T cell count were found 6 months after HAART was stopped, when treated subjects were compared with untreated subjects.

The impact of antigenic stimulation on the dynamics of simian immunodeficiency virus (SIV) replication was studied following repeated intravenous BCG inoculation of a SIV infected macaque. At the site of a delayed type hypersensitivity reaction to purified protein derivative of M. tuberculosis, a distinctive SIV variant was noted, probably as a result of the infiltration of activated antigen-specific T cell clones as opposed to infection by blood borne virus in situ. The dynamics of SIV quasispecies in peripheral blood suggests sequential waves of viral replication, illustrating the role of antigenic stimulation as a driving force in viral dissemination and pathogenesis.